21904388771 has 4 divisors (see below), whose sum is σ = 21905235000. Its totient is φ = 21903542544.

The previous prime is 21904388747. The next prime is 21904388783. The reversal of 21904388771 is 17788340912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21904388771 - 2¹⁸ = 21904126627 is a prime.

It is a super-2 number, since 2×21904388771² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21904388711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 383021 + ... + 436478.

It is an arithmetic number, because the mean of its divisors is an integer number (5476308750).

Almost surely, 2^21904388771 is an apocalyptic number.

21904388771 is a deficient number, since it is larger than the sum of its proper divisors (846229).

21904388771 is an equidigital number, since it uses as much as digits as its factorization.

21904388771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 846228.

The product of its (nonzero) digits is 677376, while the sum is 50.

The spelling of 21904388771 in words is "twenty-one billion, nine hundred four million, three hundred eighty-eight thousand, seven hundred seventy-one".